Tubular electrical grounding rod



2 Sheets-Sme L nulllunll u.

H, C, DNIELS Feb. 21, 1939.

TUBULAR ELECTRICAL GROUNDING RO* Filed June 29, 1957 Feb. 21, 1939. H.c. DANlL-:Ls

TUBULAR ELECTRICAL GROUNDING ROD Filed June 29, 1937 2 Sheets-Sheet 2Patented Feb. 21, 1939 UNITED STATES FTENT OFFIQE TUBULAR ELECTRICALGROUNDING ROD Application June 29, 1937, Serial No. 150,988

Claims.

This invention relates to an improvement in grounding-rods forelectrical installations, and more particularly to grounding-rods whichare of tubular form and adapted to be inserted into the soil to aconsiderable depth.

One ol the objects of the present invention is to provide a superiortubular electrical grounding-rod combining maximum surface area andelectro-conductivity with minimum weight.

A further object is to provide a superior driving-plunger andgrounding-rod combination whereby tubular grounding-rods ofrelatively-soft high electro-conductive material may be eiectivelyinserted into hard ground without ruinous bending or distortion of suchtubular rods.

Another object of the present invention is to provide a tubulargrounding-rod structure having means whereby a highly effectiveelectrical connection may be made between the same and a grounding-wire.

With the above and other objects in View, as will appear to thoseskilled in the art from the present disclosure, this invention includesall features in the said disclosure which are novel g5 over the priorart.

In the accompanying drawings:

Fig. l .is a perspective View illustrating a mode of installing atubular electrical grounding-rod of the present invention, adjacent atelegraph pole or the like;

Fig. 2 is a view mainly in vertical central longitudinal sectionillustrating a tubular grounding-rod as embedded in the earth andshowing a driving-plunger therein;

Fig. 3 is a broken view in vertical section showing the tubulargrounding-rod as having been driven into the earth to the desired limit,the driving-plunger being removed and the sustaining-plug installed inplace and the groundingclamp attached to the exterior of the projectingend of the tube member of the grounding-rod;

Fig. 4 is a horizontal sectional View taken on the line @-4 of Fig. 3;

Fig. 5 is a view in side elevation of the drivingplunger;

Fig. 6 is a similar view of the tube member of the grounding-rod;

Fig. I is a view in side elevation of the leadingpoint, detached; and

Fig. 8 is a similar view of the tube-sustaining plug. a

The tubular grounding-rod herein chosen for illustration includes in themain a tube member, generally designated by the reference character I0,and a leading-point rigidly attached to the lower portion of the saidtube and generally designated by the reference character II. The tubemember I 0 is preferably formed of thin-walled copper tubing which mayvary greatly with respect to length, diameter and wall-thickness, ac- 5cording to the conditions. For instance, the tube member may vary inlength from about two feet to eight or more feet and may vary inexternal diameter from about one-half inch to about one and one-quarterinch. The wall-thickness of the tube member I0 is preferably within therange of .025 to .035 approximately, to afford maximum surface area forcontact with the ground, and at the same time minimize the amount ofcopper, or the like, which is required.

The leading-point II may be made of iron and includes a conical head I2and an axial shank i3 which latter is proportioned to be driven into thelower end of the tube member I0 so as to slightly expand the same andsecure a couplinggrip thereupon. The upper surface of the said shank i3constitutes an anvil-surface i3d and the external diameter of the saidshank may, for instance, exceed the internal diameter of the tube memberIll by about .005. At the junction point of the shank I3 with the headI2, the leading-point II is formed with an upwardlyfacing shoulder Idagainst which the lower edge of the tube member I0 rests. Preferably,the largest diameter of the conical head I2 exceeds the externaldiameter of the tube member I0 by a slight amount sufficient to insurethat the said head shall form a complete passage in the soil for thesaid tube member IU, to thus minimize the friction upon the exteriorsurface of the said tube member l0 as the same is being driven into theearth in a manner as will hereinafter appear.

ln conjunction with the tubular grounding-rod above described, I employa driving-plunger, which driving-plunger is generally designated by thereference character I5 and includes a relatively-heavy cylindricalhammer-head I 6 providing a hand-grip and from which rigidly projects along rod-like driving-shank I'l freely reciprocatable in the tube memberI0 and having a length slightly in excess of the distance from theanvil-surface I3a of the shank I3 of the leading-point II to the upperedge of the tube member I0, as is shown in Fig. 2.

After the leading-point II has been pressed into the ground by theworkman as illustrated in Fig. l, the driving-plunger I5 is grasped byits hammer-head I6 and is reciprocated up and down in the tube memberI0, to thus cause the lower end of its shank II to hammer against theupper face or anvil-surface Isa of the shank I3 of the leading-point Ii.The action just described will drive the leading-point VI I into thesoil and since the said leading-point is coupled by a tight frictional twith the lower end of the tube member III, said tube member I will ineifect be drawn downwardly into the soil rather than driven thereinto.

After the tubular grounding-rod has been projected into the soil to thedesired extent in the manner described, the driving-plunger I5 iswithdrawn and a sustaining-plug I8 is installed in the upper end of thesaid tube member, Vas illustrated in Figs. 3 and 4. The said sustainingmember I8 includes a downwardly-extending cylindrical body I and arelatively-narrow head which overlaps the upper edge of the tube memberI Il. After the sustaining-member I8 has been installed in the upper endof the tube member I0, a suitable grounding-clamp such as V 2|, shown inFigs. 3 and 4, is placed upon the exterior surface of the projectingportion of the tube member IU and tightened thereupon. Thegrounding-clamp 2l may be firmly tightened upon the tube member I0without fear of crushing the same and losing the proper electricalcontact therewith, owing to the presence in the interior of the saidtube of the cylindrical body I9 of the sustaining member i8, whichlatter member not only serves to prevent collapse of Vthe portion of thetube upon which the grounding-clamp 2l is installed, but the saidgrounding-clamp also serves to hold the said sustaining member in placein the tube member l0 against withdrawal therefrom. A grounding-wire 22is connected in any approved manner to the grounding-clamp 2l and isthereafter in thorough electrical connection with the tube member I0.

By so proportioning the driving-plunger I5 and the tubular grounding-rodso that the lower end of the shank I'I of the driving-plunger imv pingesupon the anvil-surface of the shank I3 of the leading-head II before theunder face of the cylindrical hammer-head I6 of the said driving-plungercontacts the upper edge of the tube member I8, it is possible to projectthin-walled tubing such as Ii! deeply into the soil solely by draftimposed thereon. It will be appreciated in this connection that if aneffort were made to drive the thin-walled tube member IQ into the soilby hammering and pounding the upper edge thereof, such tube member I0would collapse and buckle Aafter but very slight penetration into thesoil. As before indicated, the sustaining-member or plug I8 not onlyserves to sustain the ull'- per portion of the tube member I0 fromcollapsing under the clamping action of the grounding-clamp 2i but thesaid grounding-clamp 2l serves to compress the adjacent portion of thesaidtube member against the shank I9 of the sustaining-plug I8 and thusprevents the inadvertent withdrawal of the same from the member I0. v

By means of the present invention it has been made possible to employcopper or similar relatively-expensive grounding-rod material in placeof the heavier and bulkier iron grounding-rods now most generally inuse. Not only are such iron grounding-rods of relatively-lowconductivity but they yare very apt to corrode and disintegrate in themoist soil in which they are usually employed.

If, during the operation of inserting the tubular grounding-rod into thesoil, the frictional grip of the soil upon the tube member Ill should beso severe as to cause the driving-plunger to drive the leading-point I Islightly out of the tube member IG, the under face o-f the hammer-head Iwill then come into engagement with the upper edge of the tube member I0and under these conditions the continued reciprocation of thedriving-plunger I5 will act both upon the anvilsurface Ilia as well asthe upper edge of the tube member I0.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in al1 Vrespects as illustrative and notrestrictive, and

all changes coming within the meaning and equivalency range of theappended vclaims are intended to be embraced therein.

I claim:

l. A grounding-device comprising in combination: an elongated tube; aleading-point; and interconnecting-arrangements therefor; the saidleading-point being arranged to close the lower end of the tube andhaving an upwardly extending shank, the said shank terminating in animpact-receiving surface for receiving impact from a driving-element toVdrive the leading-point axially under all conditions of groundencountered; the said tube and the said shank having such relativediameters as to provide force-fit interconnection thereof; the saidforce-rit interconnection acting Vagainst resistance to impact on theleading-point of the magnitude of ordinary ground-resistance, to causethe said tube to be drawn axially with the driven leading-point to enterground jointly therewith, and 'the said force-lit connection beingyieldable to force exceeding said ordinary ground-resistance inmagnitude, whereby under impact the said leadingpoint is driven axiallyforward relatively to the tube and 'penetration-lag of the tube withrespect to the leading-point, is effected.

2. A grounding-device comprising in combination: an elongated tube; aleading-point; and interconnecting-arrangements therefor; the saidleading-point'being arranged to close the lower end of the tube andhaving an upwardly extending shank, the said shank terminating in animpact-receiving surface for receiving impact from a driving-element todrive the leading-point axially under all conditions of groundencountered; the said tube and the said shank having such relativediameters as to provide force-lit interconnection thereof; the saidforce-lit interconnection acting against resistance to impact on theleading-point of the magnitude of ordinary ground-resistance, to causethe said tube to be drawn axially with the driven leadingpoint to enterground jointly therewith, and the said force-nt connection beingyieldable to force exceeding said ordinary ground-resistance inmagnitude, whereby under impact the said leading-point is driven axiallyforward relatively to the tube and penetration-lag of the tube withrespect to the leading-point, is effected; the said tube being arrangedto also receive impact-force whenretarded, and the said force-fitinterconnection being yieldable to permit movement of the tube withrespect to its leading-point to counteract penetration-lag of the tube.

3, A grounding-device comprising in combination: an elongated tube; aleading-point; and interconnecting-arrangements therefor; the said tubebeing open at least initially at its upper end for reciprocation of adriving-element therein; the said leading-point being arranged to closethe lower end of the tube and having a shank extending upwardly therein,the said shank terminating in an impact-receiving surface for receivingimpact from a driving-element to drive the leading-point axially underall conditions of ground encountered; the inside diameter of the tubebeing less than the outside diameter of the said shank, and the saidshank being forcibly inserted in the said tube to provide force-fitinterconnection thereof; the said force-nt interconnection actingagainst resistance to impact on the leading-point of the magnitude ofordinary ground-resistance, to cause the said tube to be drawn axiallywith the driven leading-point to enter ground jointly therewith, and thesaid force-t connection being yieldable to force eX- ceeding saidordinary ground-resistance in magnitude, whereby under impact the saidleadingpoint is driven axially forward relatively to the tube andpenetration-lag of the tube with respect to the leading-"point, iseiected; and means for limiting the penetration-lag of the said tube.

4. A grounding-device comprising in combination: an elongated tube; aleading-point; and interconnecting-arrangements therefor; the said tubebeing open at least initially at its upper end for reciprocation of adriving-element therein; the said leading-point being arranged to closethe lower end of the tube and having an abutment-shoulder and alsohaving a shank extending upwardly therein, the said shank terminating inan impact-receiving surface for receiving impact from a driving-elementto drive the leading-point axially under all conditions of groundencountered; the inside diameter of the tube being less than the outsidediameter of the said shank, and the said shank being forcibly insertedin the said tube to provide force-t interconnection thereof; the saidforce-fit interconnection acting against resistance to impact on theleading-point of the magnitude of ordinary ground-resistance, to causethe said tube to be drawn axially with the driven leading-point to enterground jointly therewith, and the said force-fit connection beingyieldable to force exceeding said ordinary ground-resistance inmagnitude, whereby under impact the said leading-point is driven axiallyforward relatively to the tube and penetration-lag of the tube withrespect to thev leading-point, is effected; means for limiting thepenetration-lag of the said tube; the said tube being arranged to alsoreceive impact-force when retarded, and the said force-fitinterconnection being yieldable to permit movement of the tube withrespect to its leading-point to counteract penetration-lag of the tube;and means comprising the abutment-shoulder of the leading-point forlimiting the counteracting movement of the said tube.

5. A grounding-device including in combination: an elongated tubeprovided with an impact-receiving surface; a leading-point having ashank terminating in an impact-receiving surface; a force-fit connectionbetween the said shank and the said tube; and a reciprocatabledriving-element provided with an impact-surface at its lower end and atits upper end, the distance between the lower and upper impact-surfacesof the driving-element being shorter than the length of the said tubeand longer than the distance normally between the respectiveimpactsurfaces of the leading-point and the tube, whereby impact isnormally delivered only to the impact-surface of the leading-point; thesaid forcet connection acting against resistance to irnpact on theleading-point of the magnitude of ordinary ground-resistance, to causethe said tube to be drawn axially with the driven leading-point, wherebythe leading-point and tube jointly enter the ground, and the saidforce-fit connection being yieldable to force exceeding ordinarygroundresistance whereby the leading-point is driven axially forwardrelatively to the tube and penetration-lag of the tube is effected toexpose the impact-surface of the tube to impact of the upperimpact-surface of the driving-element.

HAROLD C. DANIELS.

